Some electrical control circuits, such as certain automotive vehicle electrical system circuits, utilize an electronic controlling circuit to control the flow of relatively larger current in a controlled circuit. Such a controlled circuit may include an electrically powered device, such as an actuator or a motor for example, that draws much more current than the electronic control circuit can deliver. A switching device for interfacing an electronic controlling circuit with a controlled circuit should: 1) provide low heat generation to avoid potentially damaging thermal effects; 2) possess satisfactory operational reliability over its useful life; and 3) have some form of back-up, or mechanical override, in case of a fault in the electronic controlling circuit. These considerations contribute to expense of employing solid-state relay technology to interface such controlling and controlled circuits.
The present invention relates to a switching device that possesses these features while providing cost-efficient control of electric current switching, especially the switching of larger electrical currents required by certain utilization devices of an automotive vehicle.
One aspect of the present invention relates to a modular form of switching device that comprises a novel configuration of various features in addition to the switching function. The features include: switching by short duration electrical pulses so that the device does not impose continuous current drain in its operational conditions thereby avoiding the generation of significant heat; a circuit protection device, advantageously a thin-line fuse, that separably mounts in circuit-protection-device-receiving-terminals that are mounted on the device to be accessible from the exterior of the device so as to enable the circuit protection device to be mounted, and to be changed when necessary, via the exterior of the switching device; a visible indicator for indicating an open-circuited, or removed, circuit protection device, such as a blown, or removed, thin-line fuse; and an RC circuit that provides for the use of an LED as the indicator while affording certain protection for the LED.
The foregoing, along with further features and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. The disclosure includes a drawing, now briefly described.